The No1 Mark III was made up until 1916, but the "FTR" on your rifle shows it went through a "Factory Thorough Refit", meaning it was rebuilt either during or after WW1. These rifles were manufactured by 5 different manufacturers, and the only way to know who originally made this one is to see if there are any marks left of the original socket stamp (usually initials over the original model stamp).

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Gun control in Canada: making the streets safer for rapists, muggers, and other violent criminals since 1936.